As a suspension device, for example, there is known a suspension device serving as an active suspension interposed between a vehicle chassis and a vehicle axle. JP 63-176710 A discloses an active suspension including an actuator having a cylinder, a piston movably inserted into the cylinder to partition a pressure chamber in the cylinder, and a rod connected to the piston, a hydraulic pump driven by a vehicle engine at all times, a hydraulic channel that connects the pressure chamber inside the cylinder and the hydraulic pump, a pressure control valve provided in the middle of the hydraulic channel to control a pressure of the pressure chamber, and a control unit for controlling the pressure control valve.